Cutter head for dry shaver



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Nov. 15, 1960 J. F. WAHL 2,959,854

CUTTER HEAD FOR DRY SHAVER Filed Sept. 21, 1955 2 Sheets-Sheet 1 0000000 00 0000000 00 Q 0 O o o O 0 0 O O0 o o o o o o o 0 o 0o o o o o o o c o o o0 OOOOOOOOOOO WWW Nov. 15, 1960 J. F. WAHL CUTTER HEAD FOR DRY SHAVER Filed Sept. 21, 1955 UQUQUUUUUUUU 2 Sheets- Sheet 2 Z In erzfl Unite States Patent CUTTER HEAD FoR DRY SHAVER John F. Wahl, Sterling Ill., assignor to Wahl Clipper Corporation, Sterling, 11]., a corporation of Illinois Filed Sept. 21, 1955, Ser. No. 535,570

2 Claims. (Cl. 30-43) This invention relates to a cutter head for a dry shaver.

A dry shaver cutter head comprises a fixed outer blade and a movable inner blade which cooperate with each other to perform the cutting function.

One object of the invention is to provide a cutter head wherein the two blades, outside and inside, are substantially alike in physical characteristics. Both are made of perforated sheet metal which is extremely thin and resilient, and they are disposed in face-to-face bearing contact over a large area.

Another object of the invention is to provide a cutter head wherein both blades are uniformly or regionally yieldable in order to conform to facial contours. The uniform yieldability being such that the bearing contact between the two blades is not altered as the blades are distorted to conform to facial contours.

Prior cutter heads utilize a movable inner blade which is substantially rigid in character, and in most instances the inner blade is mounted in a resilient manner. In such a cutter head the resilient outer blade is able to yield somewhat because of the resilience of the mounting arrangement of the inner blade. However, when the outer blade yields, a certain amount of bearing between the two blades is lost, and the outer blade is susceptible to being broken or torn by the cutting edges of the inner blade. This difliculty is eliminated by the present invention wherein the two blades always retain a desirable bearing relationship despite even extreme distortion.

Another object of the invention is to provide a cutter head which possesses optimum characteristics from the standpoint of venting the cut facial hair. The hair drops into a large space within the inner blade and this space is open ended so the hair may be vented simply by a flick of the wrist or blowing moderately on one end.

Still another object of the invention is to provide a cutter head wherein cutting bias between the two blades may be provided by the blades themselves. Thus, in one aspect of the invention, it is unnecessary to provide any extraneous means to insure proper bias, and there is no need to provide any sort of bias adjustment.

Still another object of the invention is to provide a cutter head which is extremely economical to manufacture. The stock used in the cutter elements may be hardened prior to the fabrication of the blades. Accordingly, the manufacturer may purchase pre-hardened stock and be free of any problem of tempering the blades after they are formed. The present blades may be formed by a simple stamping operation performed on a prehardened sheet of suitable high carbon steel.

In brief, the present cutter head comprises a fixed outer blade which is suitably secured to the shaver body. The outer blade is constructed of perforated sheet metal which is extremely thin and resilient, the thickness of the outer blade being of the order of .0015 inch to insure closeness of cut and ready conformity to facial contours. i As previously mentioned, the outer blade is constructed of pre-hardened high carbon steel. The cutting portion of ice the outer blade is generally curved in cross section, as is more or less conventional.

The movable inner blade comprises a cutting element likewise made of perforated sheet metal which is extremely thin and resilient. Preferably the inner blade is slightly thicker than the outer blade, the thickness being of the order of .0030 inch. In the cutting area the inner blade is curved in cross section to conform to the curvature of the outer blade and provide face-to-face contact over a large area at least a portion of which defines a cutting region. The two blades may be assembled in such manner that the inner blade is deformed slightly (in addition to the aforesaid curvature) in order to develop a stress therein which provides cutting bias between the two blades. With the outer blade perforated and formed from prehardened high carbon steel .0015" thick, and the inner blade perforated as shown in the drawings and .0030 thick, the inner and outer blades will be very flexible and will be deformed whenever the cutting head of the shaver passes over a protuberance on the skin, such as a bony contour, etc. The inner movable blade is designed to be so flexible that when the cutting head of the shaver passes over such a protuberance it will deform locally under the resulting pressure before it can be forced away from its bearing and cutting engagement with the outer blade, so the entire face-to-face contact between the blades will be maintained over substantially the entire cutting region despite this deformation. This is what is called uniform or regional yieldability.

Other objects, advantages and details of the invention will be apparent as the description proceeds, reference being had to the accompanying drawings wherein several forms of the invention are shown. It is to be understood that the description and the drawings are illustrative only and the scope of the invention is to be measured by the appended claims.

In the drawings:

Fig. 1 is a plan view of a dry shaver, partly in section, the casing lid being removed for clarity;

Fig. 2 is a vertical sectional view through the dry shaver shown in Fig. 1;

Fig. 3 is an enlarged sectional view through the two blades of the shaver head;

Fig. 4 is a fragmentary plan view of the cutter head, a portion of the outer blade being broken away to show the inner blade;

Fig. 5 is a bottom view of a support member which forms part of the inner blade shown in Figs. 1-4;

Figs. 6 and 7 are sectional views illustrating a cutter head of the form shown in the previous figures but utilizing a modified form of connection with the driving means of the shaver;

Figs. 8 and 9 are sectional views illustrating another form of connection between the movable blade and the driving means of the shaver, and

Figs. 10 and 11 are sectional views illustrating a modified form of inner blade, the inner blade being tubular in shape.

Referring now to the drawings, and particularly Figs. 1-5, cutter head 13 of the invention is shown incorporated in a dry shaver 14. Shaver 1 4 includes a casing 15 having a removable lid 16 (Fig. 2). An electromagnet 17 and a cooperating armature 18 are disposed Within casing 15, armature 18 being mounted at 19 in the rear end of the casing.

The forward end of casing 15 includes a bearing element 20 which may or may not be integral with the rest of the casing. As here shown, bearing element 20 forms an integral part of the head end of casing 15.

An aperture 22 is provided in bearing element 20, the aperture being off center as shown in Fig. 1. A projec- 3 tion 23 of armature 18 extends through aperture 22 and engages the movable blade of the cutter head as will be seen.

Armature 18 is positioned properly for prevailing voltage conditions by means of a screw 25 which cooperates with springs 26 and 27 in a well known manner.

The cutter head 13 of the invention includes a fixed outer blade 30 which is more or less conventional. Blade 30 is formed of perforated sheet metal which is extremely thin and resilient. The thickness of outer blade 30 is of the order of .0015 inch to insure closeness of cut and desired yieldability. The sheet metal of which blade 30 is made is pre-hardened, and the blade is cut to size and perforated in a stamping operation.

The term perforated is used in a generic sense and -it contemplates openings of all practical shapes and sizes,

including elongated slots such as are shown in both blades in Fig. 4.

Opposed edge portions of blade 30 are suitably atfixed to the head end of casing 15 by means of screws 31 or the like, there preferably being at least two screws on each edge portion with a clamping bar 32 extending along each side beneath the screw heads.

Blade 30 between the edge portions is curved in cross section, as best shown in Figs. 2 and 3.

The cutter head 13 also includes a movable inner blade 35 which comprises a cutter element 36 and a support member 37 for the cutter element. As best shown in Fig. 3, edge portions 38 and 39 of cutter element 36 are received in spaced parallel grooves formed in support member 37.

Cutter element 36 is formed of perforated prehardened sheet metal which is extremely thin and resilient. The thickness of element 36 is of the order of .0030 inch. By using prehardened sheet metal the cutter element 36 may be cut to size and perforated in a single operation, and can be installed on a shaver cutting head without any subsequent heat treatment and expensive grinding and lapping operations. This result in a very important saving in the cost of manufacturing the product.

With cutter element 36 formed as described above, it will be regionally yieldable. It is noted, however, that the property of regional yieldability in sheet metal depends upon many factors. These factors include the composition of the sheet metal, its hardness, its thickness, its cross sectional shape, and the size, shape, number and distribution of any perforations. In this case, the cutter element which is .0030 inch thick, prehardened, and perforated as shown in Fig. 4 has been found by examination to be regionally yieldable, but if any of these factors are changed, the presence or absence of regional yield..- bility would have to be determined by another examination. In other words, unless a material having certain physical properties has been previously known to be regionally yieldable, it would not be possible to tell with any certainty whether the material in question has this property without an examination of it.

Between the edge portions 38 and 39 cutter element 36 is curved in cross section. The curvature, of course, conforms to that of outer blade 30 so the two cutter elements are in face-to-face contact over a large area, the contact area defining a large cutting region.

The two blades are assembled in such manner that inner cutter element 36 is deformed slightly in addition to the aforesaid curvature in order to develop a stress which provides cutting bias between the two blades. This additional deformation is illustrated in Figs. 2 and 3 by the shape of curvature which deviates slightly from that of a circular arc.

Referring to Fig. 5, support member 37 is a rectangular element, preferably of a molded Nylon, having spaced grooves 40 and 41 which receive the aforesaid edge portions 38 and 39 of cutter element 36. A pair of spaced slots 42 and 43 enter member 37 from one end to define a tongue 45 which near its free end has an aperture 46.

The bottom of tongue 45 is cut away as shown at 48 in Fig. 3 so that the tongue may be depressed within the bounding plane of the member. Projection 23 of armature 18 makes a forced or other suitable fit with aperture 46 and establishes a drive connection with support member 37. Tongue 45 is deformed downwardly somewhat in its connection with projection 23 to provide a bias which insures that support member 37 will have proper bearing relationship with bearing element 20 of the casing.

The thinness of the respective blades is such that the two blades flex together in a yieldable manner to conform to facial contours. Distortions of this character, however, do not involve loss of the face-to-face bearing contact between the two blades. Rather face-to-face contact is retained with the result that local distortions do not subject the outer blade to the likelihood of being torn or otherwise damaged by the movement of the inner blade. In other words when the shear plate is deformed the inner or cutter blade deforms to conform to the deformed shape of the shear plate so that cutting contact between the shear plate and the cutter blade is maintained over their cutting regions.

In Figs. 6 and 7 the outer and inner blades are sub stantially the same as those previously described. The main difference in the Figs. 6 and 7 form of the invention resides in the elimination of bearing element 20 of the casing. Support member 50 of the inner blade is rigidly carried by a pair of spaced arms 51 and 52 which in turn are rigidly carried by armature 53. No bearing element is required with this arrangement and the cutter element of the inner blade is yieldable to tolerate the mildly 'arcuate path of support member 50 which results from the rigid relationship with vibrating armature 53. The outer blade conforms to any deformation of the yielding inner blade, and thus the two blades are in cutting contact at all times.

Figs. 8 and 9 illustrate an arrangement which like that of Figs. 6 and 7 also eliminates bearing element 20 of the casing. In this form, support member 55 of the inner blade has a pair of spaced, triangular-shaped notches 56 which receive tapered ends 57 of a pair of spaced arms 58 and 59. These arms are rigidly mounted on vibrating armature 60. The notches 56 and the cooperating tapered ends 57 provide a pivotal relation between support member 55 and armature 60. Thus, the inner blade may travel a generally straight path while the driving means (armature 60 and arms 58 and 59) travel an arcuate path. The resilience of the inner blade permits the blade to yield to compensate for the arcuate path of arms 58 and 59 and to maintain the inner and outer blades in contact at all times.

The modification shown in Figs. 10 and 11 is characterized by an inner blade 62 wherein the cutter element 63 is tubular in shape rather than more or less semicircular as in the prior forms. Tubular cutter element 63 is carried by a support member 64 which may be related to armature 65 with any suitable connection such as those described above. Cutter element 63 is deformed slightly in addition to the circular curvature in order to provide proper cutting bias between the blades.

From the above description it is thought that the construction and advantages of the invention will be readily apparent to those skilled in the art. Various changes in detail may be made without departing from the spirit or losing the advantages of the invention.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent is:

1. A dry shaver comprising a casing, an outer shear plate mounted on said shaver, said shear plate having a perforate portion including a cutting region, an inner cutter, having a perforate portion including a cutting region, said cutter mounted in said shaver with its cutting region in contact with the cutting region of said shear plate, reciprocating driving means in said casing driving said cutter, said cutting region of the shear plate and said cutting region of said inner cutter being flexible, deformable, and resilient so that when said shear plate is deformed, said cutter deforms to conform to the deformed shape of said shear plate so that the cutting contact between said shear plate and said cutter is maintained over their cutting regions.

2. The dry shaver described in claim 1 wherein said contact between said shear plate and said inner cutter de forms both said shear plate and said inner cutter to develop a stress which provides cutting bias between them.

References Cited in the file of this patent UNITED STATES PATENTS 2,098,849 Amsler Nov. 9, 1937 2,141,582 Wimberger Dec. 27, 1938 2,174,039 Muros Sept. 26, 1939 6 Lougheed Nov. 7, 1939 Andis Apr. 2, 1940 Bruecker Mar. 11, 1941 Lynch Mar. 11, 1941 Volz June 10, 1941 Wahl Dec. 9, 1941 Raia July 14, 1942 Abrams Nov. 3, 1942 Lindholm Dec. 22, 1942 Penney Nov. 30, 1943 Jepson Sept. 7, 1954 Heye'k Aug. 13, 1957 FOREIGN PATENTS Austria July 10, 1952 Great Britain Mar. 26, 1952 

